Nonlinear behavior during NO 2  hydrogenation on a nanosized Pt-Rh catalyst sample

Barroo, Cédric; Decker, Yannick De; Jacobs, Luc; Bocarmé, Thierry Visart de

doi:10.1016/j.apsusc.2017.03.266

Cited by 11 publications

(11 citation statements)

References 42 publications

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“…Within the same pressure range, on Pt-Rh, non-linear dynamics are observed in the form of periodic oscillations over {012} regions (Figure 1.b-c), for an O 2 pressure between 2.0×10 -3 Pa and 4.0×10 -3 Pa and a H 2 pressure between 2.0×10 -3 Pa and 3.0×10 -3 Pa. This type of phenomenon has been previously reported by in the NO 2 +H 2 system over Rh, Pt and Pt-Rh [4,5]. The observation of changes in the {113} regions of Pt-Rh suggests that O(sub) and inter-facets dynamics are fully involved in this periodic process [6].…”

supporting

confidence: 81%

Subsurface Oxygen Formation during H2 Oxidation over Rh, Pt and Pt-Rh Model Nanoparticles.

et al. 2018

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supporting

confidence: 81%

Subsurface Oxygen Formation during H2 Oxidation over Rh, Pt and Pt-Rh Model Nanoparticles.

et al. 2018

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“…The analytical techniques of 1-dimensional atom probe (1DAP), field ion microscopy (FIM) and field emission microscopy (FEM) are historically designated as field emission techniques (FET) [5,[7][8][9][10][11][12][13][14][15][16][17]. With atom probe tomography (APT), these techniques are known collectively as atom probe microscopy (APM) [18,19].…”

Section: Introductionmentioning

confidence: 99%

Nanoscale Perspectives of Metal Degradation via In Situ Atom Probe Tomography

et al. 2020

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We report a unique in situ instrument development effort dedicated to studying gas/solid interactions relevant to heterogeneous catalysis and early stages of oxidation of materials via atom probe tomography and microscopy (APM). An in situ reactor cell, similar in concept to other reports, has been developed to expose nanoscale volumes of material to reactive gas environments, in which temperature, pressure, and gas chemistry are well controlled. We demonstrate that the combination of this reactor cell with APM techniques can aid in building a better mechanistic understanding of resultant composition and surface and subsurface structure changes accompanying gas/surface reactions in metal and metal alloy systems through a series of case studies: O2/Rh, O2/Co, and O2/Zircaloy-4. In addition, the basis of a novel operando mode of analysis within an atom probe instrument is also reported. The work presented here supports the implementation of APM techniques dedicated to atomic to near-atomically resolved gas/surface interaction studies of materials broadly relevant to heterogeneous catalysis and oxidation.

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“…The extent of Rh enrichment strongly depends on thermal treatment applied, its duration and crystallographic orientation of the surface. Atom Probe Tomography (APT) studies revealed that at temperatures below 500 K, Rh was drawn to the surface in nearly all regions of the alloy specimens [20,21]. However, when temperature was raised above 573 K, the Rh-enriched regions were distributed over Pt-Rh alloy nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

“…This dual behavior was explained by diffusion processes occurring normal and parallel to the local surface. This observation can have significant impact on the reaction dynamics [21]. For example, field emission microscopy (FEM) revealed oscillations under NO 2 + H 2 reaction on a Pt-17.4 at.%Rh alloy nanosized crystal at 425 K, while for pure Pt and Rh the non-linear behavior was observed at 390 K and at 450 K, respectively [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Oxygen Adsorption, Subsurface Oxygen Layer Formation and Reaction with Hydrogen on Surfaces of a Pt–Rh Alloy Nanocrystal

et al. 2020

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The oxygen adsorption and its catalytic reaction with hydrogen on Pt–Rh single crystals were studied at the nanoscale by Field Emission Microscopy (FEM) and Field Ion Microscopy (FIM) techniques at 700 K. Both FEM and FIM use samples prepared as sharp tips, apexes of which mimic a single nanoparticle of catalyst considering their similar size and morphology. Oxygen adsorption on Pt-17.4 at.%Rh samples leads to the formation of subsurface oxygen, which is manifested in the field emission (FE) patterns: for O2 exposure of ~3 Langmuir (L), {113} planes appear bright in the emission pattern, while for higher oxygen doses, i.e. 84 L, the bright regions correspond to the high index planes between the {012} and {011} planes. Formation of subsurface oxygen is probably accompanied by a surface reconstruction of the nanocrystal. The subsurface oxygen can be effectively reacted off by subsequent exposure of the sample to hydrogen gas at 700 K. The hydrogenation reaction was observed as a sudden, eruptive change of the brightness seen on the FE pattern. This reaction resulted in the recovery of the initial field emission pattern characteristic of a clean tip, with {012} facets being the most visible. It was shown that the oxygen accumulation-reduction process is completely reversible. The obtained results indicate that the presence of subsurface species must be considered in the description of reactive processes on Pt–Rh catalysts.

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Nonlinear behavior during NO 2 hydrogenation on a nanosized Pt-Rh catalyst sample

Cited by 11 publications

References 42 publications

Subsurface Oxygen Formation during H2 Oxidation over Rh, Pt and Pt-Rh Model Nanoparticles.

Subsurface Oxygen Formation during H2 Oxidation over Rh, Pt and Pt-Rh Model Nanoparticles.

Nanoscale Perspectives of Metal Degradation via In Situ Atom Probe Tomography

Oxygen Adsorption, Subsurface Oxygen Layer Formation and Reaction with Hydrogen on Surfaces of a Pt–Rh Alloy Nanocrystal

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